JPH10327426A - Video signal processing circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a video recording system where a color stripe signal being a copy control signal of the macro vision system is surely sensed with copy prevention, and also to provide a monitor system where a video image is normally displayed without sensing the color stripe signal. SOLUTION: In the case that an AGC pulse detection circuit 7 detects an AGC pulse signal from a video signal, a burst gate pulse generating circuit 9 generates a burst gate pulse. In the case of a VTR, the circuit 9 generates a burst gate pulse to extract an inverted part of the color burst signal and in the case of a monitor, the circuit 9 generates a burst gate pulse to extract a noninverting phase of the color burst signal to extract the color burst. In the case of recording, since the phase is inverted, a recording APC circuit 10 records the signal without being synchronized and in the case of reproduction, the part is not colored. On the other hand, the image is normally displayed because of the regular phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal processing apparatus which reliably responds to a macrovision type copy guard signal in a recording system, but does not respond to a reproduction system.

[0002]

2. Description of the Related Art A conventional example will be described with reference to FIGS. FIG. 3 is a block diagram of a signal processing circuit of a conventional VTR. FIG. 4 shows the waveform of the AGC pulse signal of Macrovision, and FIG. 5 shows the waveform of the Macrovision color stripe signal. FIG. 6 is a screen diagram of a 4-line version of a 21-line interval of a macrovision color stripe, and FIG. 7 is a screen diagram of a 2-line version of a 17-line interval.

First, a conventional video tape radar (VT)
The signal processing system of R) will be described. As shown in FIG. 3, the video signal is input to the AGC circuit 11. AGC circuit 1
At 1, the result of detection by the AGC detection circuit 16 is fed back to control the luminance level. The output of the AGC circuit 11 is input to the Y / C separation circuit 12. Although there are various configurations of the Y / C separation circuit 12, a low-pass filter (Y. LPF) 13 for luminance signal separation and a high-pass / band-pass filter (CH) for chroma signal separation are shown in FIG.
(PF / BPF) 14 is shown.

The output of the Y / C separation circuit 12 is input to a clamp circuit 15 for performing AGC detection and synchronization separation.
The output is input to the AGC detection circuit 16 and the synchronization separation circuit 18. The AGC detection circuit 16 outputs the signal to the luminance recording system, and the synchronization separation circuit 18 outputs a composite synchronization signal. The output of the sync separation circuit 18 is input to a burst gate pulse generation circuit 19, which generates a burst gate pulse and inputs it to the recording APC circuit 20, and is supplied to another chroma processing circuit.

The detection of the macrovision copy guard signal and the operation of the copy guard in the VTR having the above-described circuit configuration will be described. FIG. 4 shows a waveform of an AGC pulse signal for macro vision copy guard. This AGC
The pulse signal has a signal level of 117 after the horizontal synchronization signal.
A large pulse having an IRE and a pulse width of 3.0 μsec is provided at a period of 8.9 μsec following the pseudo-sync pulse having a signal level of 40 IRE. The inserted scanning lines are 12 to 19 lines of odd fields and 275 to 282 lines of even fields.

The AGC pulse signal is supplied to the AGC detection circuit 1
6, the keyed AGC is activated, a detection current flows, and the AGC circuit 11 converts the level. If the detection current exceeds a predetermined value, it is determined that the signal is a macrovision AGC pulse signal, and the detection current is further increased to compress the recording level of the video signal to 40% or less. If recording is performed on a VTR in this state, the synchronization signal is also compressed and recorded at the same time. Therefore, synchronization cannot be separated at the time of playback, and the playback screen flows or the burst gate pulse cannot be generated. Therefore, copying by the VTR can be restricted.

Next, the color stripe signal of Macrovision will be described. As shown in FIG. 5, the phase of the color burst signal in the first half of the signal is opposite to the normal phase. This color burst signal having the opposite phase is called Advanced Split Burst (hereinafter, referred to as “ASB”), and is used as a copy guard of the color signal portion. Both the normal phase and the opposite phase are constituted by about 5.5 cycles.

[0008] There are two types of the system, one in which four lines of ASB are combined as shown in FIG. 6 and provided in 21 line cycles, and one in which two lines of ASB are combined and provided in 17 line cycles as shown in FIG. It is. Lines containing ASB have disappeared color, so stripes on the screen are 11
This is called a color stripe because there are 13 books.

In the operation of the VTR, C.I. HPF / BPF14
Separates the chroma signal, and performs signal processing for recording. The ASB is extracted from the signal including the ASB by using the burst gate pulse generated by the burst gate pulse generation circuit 19, and the phase is compared by the recording APC circuit 20.
Since the extracted ASB has half the phase opposite,
Since recording is performed without being able to be drawn in by the recording APC circuit 20, the line having the ASB is not colored at the time of reproduction, and a striped screen is formed so that copying by the VTR cannot be performed.

[0010]

However, when this color stripe signal is used, in the recording system of the conventional VTR, most of the normal phase portion is gated due to variations in the timing and pulse width of the burst gate pulse. There was sometimes. For this reason, recording is performed without significantly affecting the recording system, and at the time of reproduction, the color is applied in the same manner as in the case where there is no copy guard, and copying may not be restricted. In addition, when a signal having the copy guard is input to a reproduction system such as a monitor, a correct hue may not be provided in response to an opposite phase portion. Therefore, in the conventional apparatus, the copy protection by the color stripe signal is less reliable.

According to the present invention, the color stripe signal, which is a copy control signal of the macrovision system, is reliably sensed in the recording system to prevent the copy, and the reproduction system is not sensitive to the image, and the image is displayed normally. It is an object to provide a video signal processing circuit.

[0012]

According to a first aspect of the present invention, there is provided a color stripe of a macrovision which makes the phase of a part of an AGC pulse signal of a macrovision and a color burst signal opposite to each other so that no color is formed during reproduction. A video signal processing circuit that performs copy protection in response to a copy guard signal composed of a signal and an AGC pulse detection circuit that detects the presence or absence of the AGC pulse signal. A burst gate pulse generating circuit for generating a normal burst gate pulse for extracting a color burst signal, and for generating a burst gate pulse for extracting an opposite phase portion of the color stripe signal when the AGC pulse signal is detected. And outputting a burst gate pulse to a recording system.

According to a second aspect of the present invention, there is provided an AGC pulse detecting circuit for detecting the presence or absence of the AGC pulse signal;
If a pulse signal is not detected, a normal burst gate pulse for extracting a color burst signal having no opposite phase is generated. If the AGC pulse signal is detected, a burst gate pulse for extracting a normal phase portion of the color stripe signal is generated. And a burst gate pulse generating circuit for generating the burst gate pulse.

According to the first aspect of the present invention, when a macrovision AGC pulse signal is detected from an input video signal, it is recognized that a copy-inhibited state is detected, and an opposite phase portion of a color burst signal is extracted. The recording system is surely sensitive to the copy guard signal.

According to the second aspect of the present invention, when the macrovision AGC pulse signal is detected from the input video signal, it is recognized that the copy is in the prohibited state, and the normal phase portion of the color burst signal is extracted. The reproduction system such as a monitor device is not sensitive to the copy guard signal.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS.
This will be described with reference to FIG. FIG. 1 is a block diagram of a circuit according to the embodiment of the present invention, and FIG. 2 is a timing chart of generation of a burst gate pulse according to the embodiment.

First, with regard to an embodiment of the present invention, a description will be given of a copy guard signal responsive system for a macrovision curler burst in a VTR.

As shown in FIG. 1, the video signal is supplied to the AGC circuit 1
Is input to In the AGC circuit 1, the detection result of the AGC detection circuit 6 is fed back, and the luminance level is controlled. The output of the AGC circuit 1 is input to the Y / C separation circuit 2. Although there are various configurations of the Y / C separation circuit 2, a low-pass filter (Y.LPF) 3 for separating a luminance signal and a high-pass / band-pass filter (C.HPF / BPF) for separating a chroma signal are shown in FIG. 4 is shown.

The output of the Y / C separation circuit 2 is input to a clamp circuit 5 for performing AGC detection and synchronization separation, and the leading ends of the synchronization signals before detection are aligned. The output of the clamp circuit 5 is input to the AGC detection circuit 6 and the synchronization separation circuit 8,
The signal is output from the AGC detection circuit 6 to the luminance recording system and the AGC pulse detection circuit 7. When the video signal on which the AGC pulse signal of Macrovision is superimposed is input to the AGC detection circuit 6, the keyed AGC operates, and the current flowing at this time is determined by the AGC.
The presence or absence of the AGC pulse signal is determined by the comparator of the pulse detection circuit 7.

When the AGC pulse detection circuit 7 detects a copy guard signal, it sends a command to the burst gate pulse generation circuit 9 to change the operation of the pulse. This is because the AGC pulse signal of Macrovision is not always added to the video signal, so it is equipped with a reset circuit and stops from the recording mode when the synchronization signal is interrupted or during recording, such as when switching signals. This is for resetting upon switching to the mode and terminating the operation.

The video signal that has passed through the clamp circuit 5 is taken out of the synchronizing signal by a synchronizing separation circuit 8, and the composite synchronizing signal to be output is provided by a servo system control system and other circuits (both not shown).
Supplied to The synchronization signal is input to the burst gate pulse generation circuit 9 to generate a burst gate pulse.

FIG. 2 shows the timing of the burst gate pulse generation in Macrovision. FIG. 7A shows the color burst signal, and the gate pulse when there is no copy guard is shown in FIG. In contrast, AG
When the AGC pulse is detected by the C pulse detection circuit 7, a copy guard mode is set and a burst gate pulse is generated as shown in FIG. Generated by the circuit 9 and supplied to the chroma signal processing unit.

On the other hand, the chroma signal separated by the Y / C separation circuit 2 enters the recording APC circuit 10. The phase of the color burst signal extracted by the burst gate pulse generated by the burst gate pulse generation circuit 9 is opposite to that of the color burst signal, and is recorded without being pulled in by the recording APC circuit 10.
Therefore, no color is applied to that portion during reproduction, and the copy guard is activated.

Next, the embodiment of the present invention will be described with reference to a copy guard signal responsive system for a macrovision curler burst on a monitor.

When displaying on a monitor, if a video signal reproduced by a VTR or a signal broadcast on the air has a copy guard signal that causes a color stripe, the signal does not respond to the copy guard signal and the signal does not normally function. Must be displayed. For this reason, it is necessary to use a burst gate pulse for extracting the color burst signal whose generation timing is different from that of the above-described VTR.

The burst gate pulse at this time is AG
When there is an AGC pulse in the C pulse detecting circuit 7, the mode becomes the copy guard mode, and the burst gate pulse generating circuit 9 extracts the part (normal phase part) after the color burst signal as shown in FIG. Generated by
The chroma signal separated by the Y / C separation circuit 2 is a recording APC
The burst gate pulse generation circuit 9
The phase is compared with the color burst signal extracted by the burst gate pulse generated in step (1). Since the phase of the extracted color burst signal is a normal phase, the chroma signal is processed normally. In this way, even a video signal having a macrovision copy guard can be normally displayed on a monitor.

Next, the generation timing of the burst gate pulse will be described. As shown in FIG. 2A, since the burst signal is superimposed on the back porch T in 8 to 10 cycles (11 cycles in ASB), the burst gate pulse is horizontally synchronized as shown in FIG. It is delayed from the falling edge of the signal by the time of the horizontal sync tip width t, and is generated with substantially the same pulse width as the back porch T.

FIG. 2C shows a burst gate pulse corresponding to the copy guard sensitive mode of the VTR. The rising edge rises at the same timing as usual in order to extract the opposite phase, and is 1 / 2T of half the period of the back porch T. Is a pulse that falls with a pulse width of It is preferable that the falling timing is actually shorter than the pulse width of 1 / 2T in consideration of a deviation or the like. With this pulse, a color burst of only the opposite phase portion is extracted.

On the other hand, FIG. 2D shows a burst gate pulse corresponding to the copy guard non-sensitive mode of the monitor. The pulse rises after being delayed by 2T and then falls with a pulse width of 1 / 2T. In fact, it is better to start up at a later timing than the lapse of 1 / 2T in consideration of a deviation or the like. With this pulse, a color burst of only the normal phase portion is extracted. It should be noted that a circuit based on a known technique can be generally used as a burst gate pulse generating circuit.

[0030]

As described above in detail, according to the first aspect of the present invention, when a macrovision AGC pulse signal is detected from an input video signal, it is recognized that the copy is in a copy-prohibited state, and the color is detected. Since the opposite phase portion of the burst signal is extracted, the video recording apparatus surely responds to the copy guard signal and cannot perform normal video recording. Also,
If there is no AGC pulse signal, a color burst signal is extracted as usual, so that normal signal processing without a copy guard signal becomes possible.

According to the second aspect of the present invention, when a macrovision AGC pulse signal is detected from an input video signal, it is recognized that the copy is in a prohibited state, and the normal phase portion of the color burst signal is extracted. The monitor device can display a normal image without responding to the copy prohibition signal. If there is no AGC pulse signal, the color burst signal is extracted as usual, so that normal signal processing without a copy guard signal can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram of a circuit according to an embodiment of the present invention.

FIG. 2 is a diagram showing timing of generation of a burst gate pulse according to the embodiment of the present invention.

FIG. 3 is a block diagram of a signal processing circuit of a conventional VTR.

FIG. 4 is a waveform diagram of an AGC pulse signal of Macrovision.

FIG. 5 is a waveform diagram of a macrovision color stripe signal.

FIG. 6 is a screen diagram of a 4-line version of a 21-line interval macro color stripe.

FIG. 7 is a screen diagram of a 17-line interval 2-line version of the Macrovision color stripe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AGC circuit 2 Y / C separation circuit 3 LPF for luminance 4 HPF / BPF for chroma 5 Clamp circuit 6 AGC detection circuit 7 AGC pulse detection circuit 8 Synchronization separation circuit 9 Burst gate pulse generation circuit 10 Recording APC circuit 11 AGC circuit 12 Y / C separation circuit 13 LPF for luminance 14 HPF / BPF for chroma 15 Clamp circuit 16 AGC detection circuit 18 Synchronization separation circuit 19 Burst gate pulse generation circuit 20 Recording APC circuit

Claims (2)

[Claims] 1. An AGC pulse signal of Macrovision,
A video signal processing circuit for performing copy protection in response to a copy guard signal consisting of a macrovision color stripe signal which reverses a part of the phase of a color burst signal and renders no color at the time of reproduction; An AGC pulse detection circuit for detecting the presence / absence of a signal; and if the AGC pulse signal is not detected, a normal burst gate pulse for extracting a color burst signal having no opposite phase is generated. If the AGC pulse signal is detected, And a burst gate pulse generating circuit for generating a burst gate pulse for extracting an opposite phase portion of the color stripe signal, wherein the burst gate pulse is output to a recording system. 2. An AGC pulse signal of Macrovision,
A video signal processing circuit for performing copy protection in response to a copy guard signal consisting of a macrovision color stripe signal which reverses a part of the phase of a color burst signal and renders no color at the time of reproduction; An AGC pulse detection circuit for detecting the presence / absence of a signal; and if the AGC pulse signal is not detected, a normal burst gate pulse for extracting a color burst signal having no opposite phase is generated. If the AGC pulse signal is detected, A burst gate pulse generating circuit for generating a burst gate pulse for extracting a normal phase portion of the color stripe signal, and outputting the burst gate pulse to a reproducing system.